In recent years, from a viewpoint of an improvement in energy security independent of petroleum and use of clean energy for exhaust gas free of nitrogen oxides, there has been an increasing expectation for a power generation system having a fuel cell for generating power from an electrochemical reaction of gas. Also, there is proposed a number of fuel cell power supply systems using the fuel cell. For example, PLT 1 set forth below discloses a grid-independent operation aiding apparatus for aiding a grid-independent operation of the fuel cell at the time of power outage.